Aircraft, particularly military aircraft, often utilize racks located beneath their wings and/or fuselages to carry stores and to release such stores from the aircraft upon command. The stores typically are munitions such as bombs, missiles, and rockets, but also include other items such as fuel tanks.
Typical store racks are shown in U.S. Pat. Nos. 4,043,525 and 4,347,777, which are incorporated herein by reference, in their entireties. As is well known, store racks typically include a release mechanism for selectively releasing a store from the aircraft upon command and often include one or more ejector rams for forcibly ejecting stores from the aircraft during their release. It is also known that various means can be used for actuating the release mechanisms and/or the ejector rams. Such means may include compressed springs, pyrotechnic cartridges, hydraulic systems, and pneumatic systems. Additionally, the release mechanisms and the ejector rams of any given store rack may be actuated via the same source of power or via separate unrelated sources of power.
The present invention pertains particularly to pneumatically actuated store racks, which have increasingly been utilized for supplying the power to the ejector rams to forcibly eject stores. Pneumatically actuated systems have several advantages including low weight, high reliability, low maintenance requirements, and operational safety.
Typically, compressed gas is supplied to a pneumatically actuated ejection system via a compressed gas storage system that, during flight and prior to the release of a store, maintains the compressed gas at a pressure sufficient to properly operate the ejection system. Because of this, several issues are of concern when utilizing pneumatically actuated ejection systems. In particular, throughout the flight of an aircraft, the gas storage system may vary in temperature by as much as over 200 degrees Fahrenheit. Such temperature variances can cause substantial changes in the pressure of the compressed gas stored in the gas storage system. This is a problem because, in many cases, the pneumatically actuated ejection systems are configured to be operated using compressed gas within fairly narrow and specific pressure ranges. As such, numerous methods have been developed and utilized to ensure that the gas stored in the gas storage system is maintained within the proper operating pressure range of the ejection system. One such method is to utilize an on-board heat source for heating the compressed gas within the gas storage system so as to increase the pressure of the compressed gas as needed. Another method is to provide an on-board gas compressor for adding additional compressed gas to the gas storage system to thereby increase the pressure of the stored gas as needed. It is also known to utilize vent valves to decrease the pressure of the stored gas as needed.
Despite the various developments and improvements associated with pneumatically actuated store rack ejection systems, there nonetheless remains room for further improvement.
The present invention eliminates many of the concerns associated with prior art ejection systems by providing a method of and apparatus for supplying proper pneumatic actuating pressures during store release without the need for on-board compressors or heating elements. In simple terms, the method and apparatus of the invention pertains essentially to the over-pressurizing of an on-board gas storage system such that the pressure of the gas stored therein remains at or above the proper pneumatic actuation pressure throughout all foreseeable temperature ranges. When a signal to release a store is provided, the pressure of the gas is reduced to be within the desired pneumatic actuation pressure and is then used to release the store.
In general, a first method of practicing the invention comprises the steps of providing an aircraft having a store rack and a gas storage system and attaching a store to the store rack. Compressed gas is supplied to the gas storage system via a source of compressed gas in a manner such that the gas storage system contains an amount of compressed gas. During flight, when a response signal to release the store is provided, the pressure of at least a portion of the amount of compressed gas is decreased. That portion of the compressed gas is then used to actuate the store rack and thereby jettison the store from the aircraft.
A second method of practicing the invention comprises providing a similar aircraft and attaching a store to the store rack. This method further includes supplying compressed gas to the gas storage system via a source of compressed gas in a manner such that the gas storage system contains an amount of compressed gas that has a pressure-to-temperature ratio of at least 12.0 psia/xc2x0R. The source of compressed air is then separated from the aircraft and during flight, the pressure of at least a portion of the amount of compressed gas is decreased to an actuation pressure that is within a range from 4,750 psia to 5,250 psia. Finally, the portion of the amount of compressed gas is used to actuate the store rack and thereby jettison the store from the aircraft.
A third method of practicing the invention, once again, comprises providing a similar aircraft and attaching a store to the store rack. This method further includes predicting a minimum operational temperature of compressed gas within the gas storage system during flight of the aircraft. The prediction is made with the assumption that energy is not added to the compressed gas during flight from any power source other than from ambient conditions surrounding the aircraft (which would not be the case if the gas was heated by aircraft systems or if additional compressed gas was added). This method yet further comprises identifying a desirable pressure range of compressed gas for pneumatically actuating the store rack (i.e. a minimum pressure limit and a maximum pressure limit). An initial pressure for supplying the gas storage system with compressed gas is determined in such a manner that the initial pressure would be sufficient to ensure that the compressed gas would have a pressure of at least the minimum pressure limit if the compressed gas were to have a temperature equal to the minimum operational temperature limit. Compressed gas is supplied to the gas storage system at the initial pressure. Finally, the pressure of at least a portion of the amount of compressed gas is decreased to be within the desirable pressure range and the portion of the amount of gas is then used to actuate the store rack and thereby jettison the store from the aircraft.
A first apparatus in accordance with the invention preferably comprises an aircraft, an amount of compressed gas, a store, a vent valve, a stores management system, and a dump valve. The aircraft has at least one pneumatically actuated store rack and a gas storage system and the amount of compressed gas is stored within the gas storage system. The store is attached to the store rack. The vent valve is operatively connected to the gas storage system and is selectively movable between opened and closed positions. In the opened position, the vent valve allows the amount of compressed air to communicate with an environment surrounding the aircraft and to pass through the vent valve. In the closed position, the vent valve prevents the amount of compressed air from passing through the vent valve to thereby communicate with the environment surrounding the aircraft. The stores management system is operatively connected to the vent valve and is configured to transmit a control signal indicative of an intent to release the store from the store rack. The vent valve is responsive to the control signal in a manner such that the vent valve is selectively moved from the closed position to the opened position in response to the control signal. The dump valve is also selectively movable between opened and closed positions. In the opened position, the dump valve allows the amount of compressed air to pass therethrough and to thereby actuate the store rack. In the closed position, the dump valve prevents the amount of compressed air from passing therethrough. Finally, the dump valve is also responsive to the control signal in a manner such that the dump valve is selectively moved from the closed position to the opened position in response to thereto.
A second apparatus in accordance with the invention preferably also comprises an aircraft, an amount of compressed gas, a vent valve, and a dump valve. Again, the aircraft has at least one pneumatically actuated store rack and a gas storage system and the amount of compressed gas is stored within the gas storage system. The amount of compressed gas is at a pressure in excess of 8,000 psia. The vent valve is operatively connected to the gas storage system and is selectively movable between opened and closed positions. The opened position of the vent valve allows the amount of compressed air to be in communication with an environment surrounding the aircraft and to pass through the vent valve. The closed position of the vent valve prevents the amount of compressed air from passing through the vent valve to thereby communicate with the environment surrounding the aircraft. The dump valve is also selectively movable between opened and closed positions. The opened position of the dump valve allows the amount of compressed air to pass through the dump valve and to thereby actuate the store rack. The closed position of the dump valve prevents the amount of compressed air from passing through the dump valve.
While the principal advantages and features of the invention have been described above, a more complete and thorough understanding of the invention may be obtained by referring to the drawing and the detailed description of the preferred embodiment which follow.